21181974 has 16 divisors (see below), whose sum is σ = 46215360. Its totient is φ = 6418760.

The previous prime is 21181961. The next prime is 21181997. The reversal of 21181974 is 47918112.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 160404 + ... + 160535.

It is an arithmetic number, because the mean of its divisors is an integer number (2888460).

Almost surely, 2^21181974 is an apocalyptic number.

21181974 is an abundant number, since it is smaller than the sum of its proper divisors (25033386).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21181974 is a wasteful number, since it uses less digits than its factorization.

21181974 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320955.

The product of its digits is 4032, while the sum is 33.

The square root of 21181974 is about 4602.3878584926. The cubic root of 21181974 is about 276.6870354836.

It can be divided in two parts, 21181 and 974, that added together give a triangular number (22155 = T₂₁₀).

The spelling of 21181974 in words is "twenty-one million, one hundred eighty-one thousand, nine hundred seventy-four".